Famously finicky fashion legend Karl Lagerfeld — known as The Kaiser — insisted on ordering from Nobu while all the other guests, including Vogue editor Anna Wintour, dined on lesser fare at a lavish FIT Couture Council lunch in his honor.

Lagerfeld, who has lived on a strict diet since losing 92 pounds in 2000, had sushi delivered to Avery Fisher Hall while 600 guests — who were warned not to mention it was the Chanel creative director’s birthday — ate stuffed chicken and quinoa salad.

A source told us, “Chanel reps called Nobu saying Karl needed a healthy meal of grilled fish, sushi and vegetables delivered to Lincoln Center.” A second source said, “There was also to be no mention of Lagerfeld’s birthday. Karl doesn’t acknowledge birthdays, or his age.”

Lagerfeld, who’s believed to be 77, seemed miffed at having to step away from work, telling The Post: “It’s collection week. People have better things to do than eat lunch with strangers.” And while he recently designed a special bottle for Diet Coke, he sipped Diet Pepsi, because it was all they were serving.

Guinness told us Lagerfeld was “very young in spirit,” adding, “I’m horrible with birthdays. I don’t even celebrate my own birthday, either. Maybe that’s because it’s in November and it’s cold and gray.”

At a Chanel dinner attended by the top editors Thursday night at 82 Mercer, Lagerfeld was given his own redecorated private bathroom. A spy reports that staff were seen taking down the “disabled” sign from the door “to avoid any embarassment.”